Unite States me lnventor Ellis 11. Born Columbus. Ohio Appl. No. 578 Filed Dec. 5, 1970 Patented Dec. 11, 1972 Assignee Abex Corporation New York, NY.
ANTISLACK UNIT 9 Claims, 7 Drawing Figs.
U.S. Ci 226/183, 74/23024, 226/184 Int. Cl B65h 79/00 Field of Search 226/ l 8 l  References Cited UNITED STATES PATENTS 1,653,062 12/1927 Rieske 2,326,671 8/1943 Patterson,Jr.. .7 3,339,424 9/1967 Humphrey Primary Examiner-Allen N. Knowles Attorneyl(inzer, Dorn and Zickert ABSTRACT: Antislack unit for maintaining tension on cable including a sheave with a hub having a periphery against which a cable may bear, a pair of clamping sideplates coacting with the hub periphery to selectively clamp the cable thereon, and spring, plates normally urging the clamping side plates on nonclamping position, and an activator along the hub periphery for moving the clamping sideplates into cable clamping position at the area of the activator.
PATENTED JAN] 1 I972 SHEET 1 BF 4 PATENTED m1 1 1972 3,633,809
SHEET 3 BF 4 /,\'v15m' 0R E LLIS H. BORN BY 12 JM/W ATTORNEYS PATENTED JAN! 1 1972 SHEET '4 OF 4 50K a m. a 7 Q Q m I m J Q fin MN Q. I. o o WK Q R o I @N a 0 A); T Q L 0 mm QB w mQE INVENTOR ELLIS H. BORN BY 6 arm/W ATTORNEYS ANTISLACIK UNIT This invention relates in general to an antislack unit for handling cable or wire rope to maintain tension on the cable when it is being payed out or taken in from a drum, and more particularly to an antislack sheave that selectively grips the cable when handling same.
The antislack unit of the invention is especially useful in the handling of cable for transferring articles between two moving ships at sea, although it can equally well be used wherever there is a necessity to apply tension on moving cable. For example, the antislack unit could be employed with a cable-hauling arrangement in lumbering operations.
The problem in handling cable between moving ships at sea arises in the necessity to maintain the cable under sufficient tension to prevent goods being transferred from being lost during the transfer operation, as more completely explained in U.S. Pat. No. 3,361,080. It is important to prevent cable from backlashingbr becoming bird-caged as it is payed out or taken in from a motor driven drum or winch. The antislack unit of the invention operates to pull the cable under tension from the drum as it is being payed out, and to maintain tension on the cable when it is being taken in. One type of antislack unit is illustrated in U.S. Pat. No. 3,388,890, wherein a set of pressure rollers coact with a sheave to force the cable into a groove on the sheave and maintain frictional gripping between the sheave and cable. This type of unit and others that have been similarly designed are hard on cable wear, thereby causin g frequent replacement of cable.
The antislack unit of the present invention overcomes the above-mentioned difficulty in materially reducing cable wear, while providing the necessary cable tension during cable-handling operations. The unit of the invention includes a sheave having a hub with a peripheral cable-bearing surface, a pair of side clamping plates coactin g with the bearing surface to selectively clamp the cable under controlled pressure and provide frictional engagement thereof, and a pair of spring plates mounting the side clamping plates and continually urging the clamping plates into nonclamping position. An actuator in the form of a pressure roller arrangement is arranged at one point along the periphery of the sheave for selective movement and engagement with the side clamping plates to urge them into clamping position with the cable in the area of the actuator. Hydraulic cylinders are provided to operate the pressure roller arrangement and to apply a predetermined force necessary to obtain the proper tension on the cable. A motor drives the sheave. The engagement of the side clamping plates with the cable is such that as the cable enters or leaves the engaging area defined by the actuator it does not scrub on the sheave, thereby materially reducing cable and sheave wear, but especially cable wear to enhance the life of the cable.
It is therefore an object of the present invention to provide a new and improved antislack unit for use with cable-handling operations to maintain proper tension on the cable when it is moving.
Another object of this invention is in the provision of an antislack unit having a sheave with movable clamping plates to selectively clamp the cable to the sheave, and an actuator for controlling the clamping action of the clamping plates, wherein the clamping plates effect engagement at one area so that the cable coming onto and off of the sheave is not subjected to any appreciable amount of wear.
Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawing, wherein like reference numerals refer to like parts, in which:
FIG. 1 is a sectional view taken through an antislack unit according to the invention and illustrating schematically hydraulic circuitry that may be employed with the unit and showing the parts in cable engaging position;
FIG. 2 is a top plan view of the antislack unit shown in FIG. 1 and illustrating particularly the sheave and pressure roller arrangement;
FIG. 3 is a fragmentary sectional view of a part of the antislack unit of FIG. 1 and in particular the cable gripping portion of the sheave and the pressure roller arrangement, wherein the pressure roller is backed off to illustrate the clamping plates in nonclamping position;
FIG. 4 is a fragmentary view of a section taken through a modified antislack unit which differs from the embodiment of FIG. 1 in providing a modified pressure roller arrangement;
FIG. 5 is a view similar to FIG. 4 illustrating a still further modification of a pressure roller arrangement;
FIG. 6 is a top plan view of a portion of the antislack unit shown in FIG. 5 to illustrate the roller support and its relation with the sheave; and
FIG. 7 is a fragmentary elevational view taken substantially along line 77 of FIG. 6, and with some parts omitted for purposes of clarity.
The antislack unit of the invention is especially useful to tension cable or wire rope, and constitutes an improvement over heretofore known devices in that cable wear is substantially reduced thereby enhancing cable life. Further, sheave wear is also reduced. Wear reduction is accomplished by a manner in which the cable is gripped by the sheave as it is handled by the sheave. In this regard, cable gripping plates extending circumferentially of the sheave are moved into cable gripping position at the point along the sheave where the cable is fully received by the sheave by means of an actuator in the form of a pressure roller arrangement.
Referring particularly to the embodiment of FIGS. 1 to 3, the antislack unit includes a sheave l1, and a pressure roller arrangement 12. The pressure roller arrangement 12 coacts with the sheave 11 to selectively grip a cable 13 in the area of the sheave at the pressure roller arrangement, to thereby tension the cable as desired.
The sheave 11 includes a hub 14, a pair of clamping sideplates l5, and a pair of spring plates 16 mounting the clamp sideplates 15 onto the hub 14. The hub 14 is centrally bored for mounting on a drive shaft 17 to corotate therewith by means of a key 18. A fluid motor 19 drives the shaft 17.
The spring plates 16 are annular and secured at their inner periphery to the hub by means of a plurality of fasteners such as bolts 20. The outer ends of the spring plates 16 are fastened to the inner ends of the annularly shaped clamping sideplates 15 by means of a plurality of machine screws 21. Accordingly, the spring plates 16 are in opposed relation, as are the clamping sideplates 15, and the clamping sideplates 15 are resiliently mounted on the hub 14. Outward of the spring plate mounting bolts 20, the hub is relieved or recessed at 22 so that the spring plates may flex toward each other. Radially outward of the recesses 22, the hub is further recessed at 23 to provide space for receiving the clamping sideplates, and to enable flexing toward each other of the clamping sideplates during the gripping and nongripping operation. The recesses 23 define therebetween an outer annular hub section 24, the very end or periphery thereof at 25 constituting a cable bearing surface. While the cable bearing surface is preferably arcuate in form as shown, it could be fiat or otherwise shaped if desired. It should be noted that the cable bearing surface is positioned inwardly of the outer ends of the clamping sideplates, and coacts with the sideplates to define a groove into which the cable 13 may be received. The inner edge portions 26 of the clamping sideplates are tapered to facilitate the movement of cable into the groove of the sheave.
The free spacing of the clamping sideplates 15 is limited by a plurality of bolts 27 which extend through the clamping sideplates and the outer portion 24 of the hub 14. These bolts further handle torquing forces applied to the clamping sideplates during operation of the unit. Spacers 28 about the bolts 27 coact with the bolt head and nut, together with the hub portion 24 to define the proper limits of the movement of the clamping sideplates. Elastomeric O-rings 29 may be provided between the clamping sideplates and the outer hub portion 24 inward of the bolts 27 to prevent the entry of water or other undesirable matter into the interior of the sheave.
The pressure roller arrangement 12 shown in the embodiment in FIG. 1 includes a roller 30 bearingly mounted on a shaft 31 extending parallel to the sheave shaft 17. The roller shaft 31 is suitably supported to enable movement thereof toward and away from the sheave 11 by means of a pair of hydraulic cylinders 32. The outer periphery of the roller is grooved to define a pair of axially spaced flanges 33 having inner tapered surfaces 34 which coact with outer tapered surfaces 35 formed on the outer ends of the clamping sideplates to cause closing movement of the clamping sidepiates when the roller is moved toward the sheave 11. The tapered surfaces 34 and are included oppositely to mate and enable a camming action to be performed on the clamping sideplates when the roller is engaged therewith. As the roller 30 moves toward the sheave 11 it drives the clamping sideplates 15 toward each other against the force of the spring plates 16 to engage the cable 13 in a clamping or gripping relationship. The degree of movement of the roller 30 relative to the clamping side plates 15 determines the amount of clamping effected on the cable 13. Moving of the roller 30 away from the sheave allows the spring plate 16 to separate the clamping sideplates 15 and disengage from the cable 13 to release the cable. The clamping action effected by the roller 30 is only in the area of the roller, and therefore cable coming onto or off of the sheave on opposite sides of the clamping area defined by the roller 30 will not scrub or unduly scrape against the clamping sideplates, thereby not effecting wear on the cable as it moves onto and off of the sheave. The cable may be arranged to be trained about any portion of the sheave desired, but the illustration in FIG. 1 where the showing of the cable at the left.
side of the sheave in nonclamping engagement with the sheave is intended to merely show the two conditions. However, FIG. 3 also illustrates the nonclamping engagement with the the pressure roller 30 as related to the clamping sideplates 15.
As already explained, the antislack unit of the invention is useful for maintaining tension on cable as it is payed out or taken in from a winch, and FIG. 1 illustrates the winch diagrammatically at 36. Hydraulic circuitry for driving the winch, the sheave, and the pressure roller arrangement is synchronized and may take any desired form, such as any of the forms illustrated in US. Pat. No. 3,388,890. The circuitry illustrated in FIG. 1 is like one of the forms in the patent and is illustrated for facilitating the understanding of the present invention. This arrangement comprises an electric motor 37 for driving a variable volume fluid pump 38 at a constant speed. The pump 38 is hydraulically connected to the winch drum drive motor for the winch 36 and drives the winch motor at a variable speed and in opposite directions depending upon the setting of the hanger position of pump 38. The hanger setting may be controlled either manually or by an automatic control system. The motor for the winch is mechanically coupled to the winch drum so that the winch motor controls speed of rotation of the drum, and the rate at which the cable 13 is payed out or taken in from the drum.
The electric motor 37 also drives a constant volume fluid pump 39 at a constant speed. The intake port of the pump 39 is connected to a tank or fluid reservoir 40 by a conduit 41, while the outlet port is connected to the intake port of the fluid motor 19 by pressure conduits 42, 43 and 44, The exhaust port of the fluid motor 19 is connected to the tank 40 through conduits 45 and 46.
A pressure relief valve 47 is arranged between the pressure conduit 42 and tank 40, and includes an inlet port 48 connected to the pressure conduit 42 through conduit 49, and an exhaust port 50 connected to an exhaust line 51 leading to tank 40. The pressure relief valve 47 also includes a vent port 52 connected to a low pressure line 53 and tank 40 through a solenoid actuator valve 54. Conduit connects the vent port 52 of the pressure relief valve 47 to the solenoid valve 53. The connection between the pressure relief valve 47 and the solenoid valve 54 is such that energization of the solenoid 56 of the solenoid valve 54 blocks the free flow path between the inlet port 48 of the pressure relief valve and the low pressure or exhaust line 53. Accordingly, when the solenoid 56 is energized, pressure in the conduits 42, 43, 44 must be equal to the pressure required by the adjustment of the pressure relief valve 47.
High-pressure conduit 43 connects through conduits 57, 58, and 59 one end of the hydraulic cylinders 32 and the other ends of the cylinders are connected to tank 40 through lines 60, 61, 62 and 46. Accordingly, when the solenoid 56 is energized, a pressure differential is established between the opposite ends of the cylinders 32 to actuate same and move the pressure roller 30 toward the sheave 11 to cause cable engagement with the side clamping plates 15.
In operation, the pump 39 supplies a constant volume of fluid to the conduits 42, 43, 44, 57, 58, 59 and 49, whether the winch drum is paying cable in or out. The pressure of the fluid in these conduits is determined by the setting of the pressure relief valve 47 and the condition of the solenoid valve 54. If the solenoid 56 is energized the entire volume of pump 39 must pass through the fluid motor 19 and/or the pressure relief valve 47 and back to tank 40. The pressure of the fluid ahead of the solenoid valve 54 is operative to actuate the fluid motor 19 so as to pull cable off the winch drum while the which drum is paying out cable or to oppose rotation of the fluid motor 19 if the drum is taking in cable. The volume of fluid flowing through motor 19 is controlled by the speed of the cable passing over the sheave 11. It should be appreciated that the hydraulic circuitry forms no part of the present invention, but it is only shown to illustrate the operation of the antislack unit of the invention. The fluid flow output from the constant volume pump 39 bypasses the relief valve 47 when the solenoid 56 is deenergized and the valve 54 is open, thereby permitting the fluid flow to go to tank 40.
Referring now to FIG. 4, another embodiment of the invention is illustrated which differs from the embodiment of FIG. 1 only in the pressure roller arrangement which is here designated as 12A. This arrangement includes a roller mounting bar 63 having opposed oppositely inclined portions 64 and 65 for receiving roller shafts 66 upon which are bearingly supported pressure rollers 67. The inclined relation of the roller support bar portions 64 and 65 incline the axis of rotation of the rollers 67 so that the outer surface 67a of the rollers are substantially parallel at the point of engagement with the tapered surfaces 35 of the side clamping plates 15. The axes of the rollers 67 extend normal to the axis of the sheave shaft 17. As the rollers are moved toward the sheave, and engage the side clamping plates 15, they cause the side clamping plates to move toward each other into clamping relation with the cable 13, in the same manner as the operation of the pressure roller 30 of the first embodiment. A pair of hydraulic cylinders 68 provide the driving force for driving the rollers toward the sheave. High-pressure conduits 69 and 70 are connected in common to the outer ends of the cylinders 68 while exhaust conduits 71 and 72 are connected to the inner ends. The further connection of the fluid conduits or lines may be in accordance with the hydraulic circuitry employed such as that shown in FIG. 1. The operation of this embodiment is substantially identical to that shown in FIG. 1 in that side clamping plates of the sheave are forced into cable engaging position when pressure rollers 67 are driven toward the sheave, and allowed to move to cable disengaging position when the rollers are permitted to return. It will be appreciated that suitable springs may be provided for effecting return of the pressure rollers when the high-pressure fluid in the high-pressure lines is diverted to tank.
A further embodiment of the invention is illustrated in FIGS. 5 to 7, which differs from the other embodiments only in the pressure roller arrangement which is here generally indicated as 128. It should be appreciated that the construction of the sheave is the same in each of the embodiments. The pressure roller arrangement 128 in this embodiment includes a pair of roller support arms 73, one on each side of the sheave. Each arm is pivotally mounted at one end to a fixed support 74 which is in alignment with the sheave. A floating hydraulic cylinder 75 is mounted between the other ends of the arms. The opposite ends of the hydraulic cylinder are preferably mounted to the arms. A high-pressure line 76 connects to one end of the cylinder 75, while an exhaust line 77 connects to the other end of the cylinder. Pressure rollers 78 are bearingly supported on the arms 73 and positioned to be in alignment with the outer ends of the side clamping plates 15. In this embodiment, it is not necessary to taper the outer end edges of the side clamping plates 15. The rotational axes of the pressure rollers 78 are in alignment with the longitudinal axes of the arms 73 and normal to the rotational axis of the sheave 11. The operation of this embodiment is similar to the other embodiments in that high-pressure fluid in the cylinder 75 forces the outer ends of the arms 73 toward each other to drive the pressure roller 78 into engagement with the outer surfaces of the side clamping plates 15, and force the side clamping plates into engagement with the cable 13. Removal of the high pressure from the high-pressure line 76 allows the outer ends of the areas 73 to separate and pivot on the supports 74 to move the pressure rollers 78 away from the side clamping plates and allow the spring plates 16 to return the side clamping plates into a cable nonengaging position. Because the actuating cylinder 75 is floating, it will effect substantially equal movement to both side clamping plates and by self-aligning.
it will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.
The invention is hereby claimed as follows:
1. An antislack unit for maintaining tension on cable, said unit including a sheave having a hub adapted to be mounted on a shaft driven by a motor, said hub having an outer annular circumferential cable bearing surface against which the cable engages, and gripping means resiliently mounted on said hub for gripping the cable at any point therealong during rotation thereof, said gripping means including a pair of annular radially extending clamping plates one on each side of the cable bearing surface and being normally in nongripping relation with the cable annular spring plates mounting the clamping plates to said hub, and pressure roller means mounted at one point along the circumference of said sheave to selectively cause said gripping means to be in variable gripping relation with he cable at said one point.
2. An antislack unit as defined in claim 1, wherein said pressure roller means includes a pair of arms pivotally mounted at one end to a fixed support, one on each side of the sheave, and movable through planes extending normal to the rotational axis of the sheave, a roller carried by each arm rotatable on an axis normal to the rotational axis of said sheave and adapted to engage the outer sides of said clamping side plates and to force them together into cable engaging position, and actuating means at the outer free ends of said arms for driving said arms.
3. An antislack unit as defined in claim 2, wherein said actuating means includes a hydraulic cylinder mounted between the outer free ends of said arms.
4. An antislack unit as defined in claim 1, wherein said pressure roller means includes a roller bearingly mounted on a shaft to rotate on an axis substantially parallel with the rotational axis of said sheave, said roller having a pair of spaced flanges with oppositely and outwardly inclined surfaces, said clamping side plates having inclined cam surfaces adapted to mate with the roller flange surfaces, and actuating means for moving said roller toward said sheave to force said clamping side plates into cable engaging position.
5. An antislack unit as defined in claim 4, wherein said actuating means includes a hydraulic cylinder.
6. An antislack unit as defined in claim 1, wherein said pressure roller means includes a support bar extending substantlally parallel to the rotational axis of said sheave and at the periphery thereof and movably mounted to move toward and away from the sheave, a pair of rollers rotatably carried on said support bar rotatable on axes normal to the rotational axis of said sheave and at an incline relative the radial lane of the shave, said rollers adapted to engage the outer e ges of said side clamping plates and force the plates together in cable engagement position when the rollers are moved toward the sheave, and means for driving said support bar and rollers toward said sheave.
7. An antislack drive unit for handling cable comprising, a sheave including a hub adapted to be mounted on a driven shaft, a circumferential cable bearing surface on said hub, a pair of metal clamping sideplates coacting with the cable bearing surface, and spring means resiliently mounting the side plates to the hub and normally positioning the plates in a nongripping relationship with a cable at the cable bearing surface, and pressure operated means at one point along the side plates for selectively urging said plates only at said point together into gripping relation with the cable.
8. In combination with a drum having cable stored thereon and a motor driven drive mechanism for rotating said drum to pay out or take in cable, an antislack unit operable to maintain tension on the cable when said drum is rotated to pay out or take in cable, said unit comprising a sheave mounted for rotation, a motor for driving the sheave, and activating means coacting with the sheave to cause frictional clamping of the cable at one point along the sheave when maintaining tension thereon, said sheave including a hub having a circumferentially arranged cable bearing surface, and metal clamp means on said hub coacting with said bearing surface normally in cable nonclamping position, and said activating means having an actuator for selectively engaging and activating said clamp means, and means driving said actuator, said clamp means including a pair of spring mounted clamping plates coacting with the bearing surface to define a cable groove, which clamping plates upon being driven together clamp the cable to the sheave.
9. The combination as defined in claim 8, wherein said actuator includes hydraulically driven pressure roller means for forcing said clamping plates together.